In recent years, as electronic devices decrease in size and thickness, portable electronic device, such as, notebook computers, mobile telephones, are widely used in today's business scenes. In the event that an alternating current (AC) power is not available, electronic devices, typically including notebook computers, will be electrically driven by rechargeable batteries loaded therein. It will thus, be desirable for most users that the electronic devices run longer before the battery runs down.
An approach in prolonging the battery drive time period is to precisely control the energy being consumed by a display unit of the electronic device. When a user does not use the electronic device over a time period, the display unit will enter a sleep mode.
However, in the described above approach the amount of energy saved is limited, which does not efficiently prolong the battery drive time.
Accordingly, what is needed is an energy saving system which can overcome the above-described problem and meet user's needs.